1. Field of the Invention
The present invention relates to a golf club, and more particularly, to a golf club wherein the golf club shaft has an improved configuration.
2. Description of the Related Art
When a player strikes a golf ball with a golf club, a club shaft of the golf club receives a load or shock due to impact of a club head and the golf ball. Here, various stresses are applied to the club shaft. What influences most to the characteristics of the club shaft among those stresses is bending stress which is generated by the striking point of the club head and the grip point of the club shaft spaced as much as the length of the club shaft, and torsional stress which is generated by the striking point of the club head and a club shaft connector spaced from each other. Further, the shock which is generated at a moment the golf club strikes the golf ball is preferably not transmitted to a user but absorbed by the club shaft.
If the strength of the club shaft is too low, the club shaft is excessively deformed when striking the golf ball and cannot strike the golf ball accurately. If the elasticity of the club shaft is low or the strength of the club shaft is too high, excess shock is transmitted to the human body. Thus, it is preferable that the club shaft has proper strength and elasticity.
In consideration of the foregoing matters, club shafts which are most widely used include a metal club shaft which includes metal alloys such as steel alloys, aluminum alloys, etc. and a graphite club shaft which includes fibers that are reinforced by epoxy resin and so on.
Among them, the metal club shaft has been first to be commercial and still widely used with continued improvement. The strength of the metal club shaft with respect to load is isotropic and represents uniform strength against tensile load or compressive load and shearing load. Accordingly, the metal club shaft is easily designed and manufactured without having to consider directions at the time of manufacture and has uniform and strong properties against bending stress and torsional stress. However, the metal club shaft has more specific gravity than the graphite club shaft but less tensile strength than the graphite club shaft. The metal club shaft has such an issue that it has less strength to weight than the graphite club shaft.
Meanwhile, the graphite club shaft is weak to a load in a direction opposite to the direction of fibers, and the design and manufacturing process of the graphite club shaft are complicated. However, the graphite club shaft may be manufactured to have proper strength according to the direction and laminating method of the fibers and has a far lower specific gravity than the metal club shaft. Thus, the graphite club shaft generally has better durability against weight than the metal club shaft. The graphite club shaft has a laminating configuration and thus has less torsional strength than the metal club shaft. The graphite club shaft is cured by epoxy resin and has stronger brittleness than the metal club shaft. Thus, the graphite club shaft is easily cracked or broken by external shock.
Accordingly, it would be preferable to provide a graphite club shaft that absorbs shock arising out of the striking of a golf ball, stabilizes swing speed and improves flight distance of the golf ball.